As a method for drilling processing of a laminated board or a multi-layer board that is used in a printed wiring board material, a method involving conducting hole boring processing by placing, as an entry board, metal foil of aluminum or the like used alone or a sheet obtained by forming a resin composition layer on a surface of the metal foil (hereinafter, the sheet is usually referred to as “entry sheet for drilling”, or also simply referred to as “entry sheet”) on the top of one laminated board or multi-layer board or a plurality of laminated boards or multi-layer boards piled has generally been adopted. Although commonly a “copper clad laminated board” is often used as the laminated board, the laminated board may be a “laminated board” that does not have a copper foil on an outer layer.
In recent years, the progress of high densification, improvements in productivity, reduction in cost, and improvements in reliability have been demanded for the laminated board or the multi-layer board that is a printed wiring board material, and high quality hole boring processing such as improvements in hole position accuracy has been required. In order to meet these demands, a processing method for hole boring using a sheet comprising a water-soluble resin such as a polyethylene glycol (see, for example, Japanese Patent Application Laid-Open No. 4-92494) has been proposed. Moreover, a lubricant sheet for hole boring obtained by forming a water-soluble resin layer on metal foil has been proposed (see, for example, Japanese Patent Application Laid-Open No. 5-169400). Furthermore, an entry sheet for hole boring obtained by forming a water-soluble resin layer on aluminum foil on which a thin film of a thermosetting resin is formed has been proposed (see, for example, Japanese Patent Application Laid-Open No. 2003-136485).
Moreover, an auxiliary material having a three layered-structure comprising a lubricating layer/ a composite material layer/ a support material, in which auxiliary material nano-structured powder is blended in a composite material layer, has been proposed (see, for example, Japanese Patent Application Laid-Open No. 2007-281404 and Japanese Utility Model Registration No. 3134128), and molybdenum disulfide has been referred as the nano-structured powder.